Pressure sensitive adhesive constructions which include a center release liner with pressure sensitive adhesive layers on both sides thereof are known in fiberglass insulation industry and used commercially. Such constructions are described in U.S. Pat. Nos. 4,157,410; 4,389,270; and 4,584,217 to McClintock (one of the inventors herein), for example. These patents teach that both pressure sensitive layers are generally the same material.
These commercial adhesives are of relatively complex construction. Consequently, the industry has attempted for years to go to a simpler construction, viz. less layers or coatings in the sandwich. They have been unable to provide a simpler adhesive construction for insulation of pipe that allowed the insulation to be readily packaged and handled without the adherent surface being protected from being soiled, bent or wrinkled during packaging and handling, which creates installation difficulties and increases the cost and labor.